by Nightwatch on 29 May 2010 21:16
I tried the same thing recently, well, a few months ago, to be correct. I tried with different softwares up to the mighty Adobe Premiere Pro and its attachments (tried even Adobe Encore) but the thing is that if the original video has not been recorded in separate music channel(s) and video channels, then it's not possible to separate the music channel. That's true, unless the person is very professional and he would manage the filter frequencies of the music from the frequencies of the normal noise and sounds in the video (film sounds, effects, dialogue, etc.)
depends on your video's situation. A lot of software not freeware and they are rather expensive, but it's almost always possible to get them on trial basis for a limited time, at least.
Do you know if the video has multi dedicated tracks for sounds and visuals?